1. Field of the Invention
This invention relates to annular seals against the flow of fluid along a shaft, for example for a marine propeller shaft where it is necessary to provide seals against the entry of sea water, and against the escape of lubricating oil from a bearing housing in either direction along the shaft.
2. Description of the Prior Art
British Pat. No. 1478273 (Howaldtwerke) teaches an annular seal in the form of an elastomeric member but such a seal has been capable of sufficient deformation due to pressure differences across it to displace it from its correct sealing position, and to cause it to rub on the shaft causing losses.